The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various methods and structures to form charge pump circuits. A charge pump circuit generally was a circuit that received a voltage and produced an output voltage that was greater than the received voltage value. In some cases, the output voltage was inverted to create a negating voltage from a positive voltage source. FIG. 1 generally illustrates a typical prior art charge pump circuit 100. The prior charge pump circuit 100 received a voltage between a voltage input 102 and a ground reference 101. An oscillator power supply 104 generated a voltage which was used by an oscillator 103. Oscillator 103 provided a train of pulses that switched between ground potential 101 and the potential of generated by supply 104. The output of oscillator 103 charged a pump capacitor 107 which in turn charged an output capacitor 110 to produce an output voltage between an output 111 and ground 101. The output voltage was referenced to ground 101 and was a voltage approximately equal to the voltage on input 102 plus the voltage of the pulses of oscillator 103.
One problem with the prior art charge pump circuit was that the voltage across the output capacitor was referenced to ground. The ground reference prevented the prior art charge pump circuit from being used when a different type of reference was needed. Another problem was the value of the output voltage. When the input voltage changed, the value of the output voltage also increased. Thus the output voltage varied. Additionally, the voltage value of the pulses from oscillator 103 was fixed and could not easily be adapted for different values of input voltage 102. The fixed nature of the voltage of the pulses from oscillator 103 could not easily be changed regardless of the value of the input voltage.
Accordingly, it is desirable to have a charge pump circuit that is not referenced to ground, that can easily adapt the output voltage for different values of the input voltage, and that can easily change the voltage value of the pulses from the charge pump oscillator.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of a metal oxide semiconductor (MOS) transistor or an emitter or a collector of a bipolar transistor, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention.